rom the
lateral and ventral surfaces of _Ligamentum depressor mandibulae_. The
insertion is fleshy on the posterior surface of the lower mandible,
posterodorsal to the insertions of _partes superficialis medialis et
lateralis_ (figs. 4, 9, 10, 13 and 14).

The parts of _M. depressor mandibulae_ are difficult to distinguish
from one another because of considerable intermingling of fibers.

~_M. pseudotemporalis superficialis._~--The origin is fleshy from the
posterior wall of the orbit, dorsal to the foramen of the trigeminal
nerve, lateral to the origin of _M. protractor quadrati_ and medial to
_M. adductor mandibulae externus profundus_. The insertion is by means
of an aponeurosis that bifurcates at the point of contact with the
mandibular ramus of the trigeminal nerve, which is at the level of the
orbital process of the quadrate (except in the Mourning Dove where the
division is more anterior), and which inserts as two tendons on the
dorsomedial edge of the lower mandible posterior to the insertion of
_M. pseudotemporalis profundus_. The lateral tendon is superficial to
the dorsomedial edge of _M. adductor mandibulae externus_, and
converges with the aponeurosis of _pars profundus_ of that muscle and
inserts with it on a tubercle near the dorsomedial edge of the
mandible anterior to the insertion of _M. adductor mandibulae
posterior_ as mentioned before. The anterior half of the medial tendon
lies ventral to the lateral edge of _M. pseudotemporalis profundus_ and
the mandibular ramus of the trigeminal nerve. All of the fibers of the
muscle insert on the posteroventral surface of the aponeurosis before
it divides. Part of _M. pseudotemporalis profundus_ also lies ventral
to the medial tendon of _M. pseudotemporalis superficialis_ and, in
effect, the tendon is imbedded in the substance of _M. pseudotemporalis
profundus_ as it proceeds anteriorly. The trigeminal nerve leaves a
slight impression on the ventral surface of the muscle near its origin
(figs. 1, 3, 11, 13, 14, 15 and 16).

~_M. adductor mandibulae posterior._~--The origin is fleshy from the
anterodorsal and anterior surfaces of the quadrate body, from the
anterodorsolateral, medial and anterior surfaces of the orbital process
of the quadrate. The muscle also has an origin from the otic process of
the quadrate, partly fleshy and partly by a slight aponeurosis. The
insertion is fleshy on the dorsal and lateral surfaces of the mandible
immediately anterior to